Uji Bakteri Koliform dan E Coli Metode MPN

Summary

The video demonstrates a laboratory procedure for testing coliform and E. coli bacteria using the MPN (Most Probable Number) method. It outlines the materials required, such as lactose broth medium, distilled water, test tubes, and Durham tubes. The process involves sample dilution, preparation of lactose broth, sterilization using an autoclave, and inoculation of samples into test tubes. Afterward, Durham tubes are inserted for gas detection. The samples are incubated for 24 hours at 37°C to observe bacterial growth. The video emphasizes aseptic techniques throughout the experiment to ensure accurate results.

Takeaways

• 🧪 The experiment involves testing for coliform and E. coli bacteria using the MPN method.
• 🥄 Necessary materials include lactose broth, distilled water, test tubes, spirit burner, Erlenmeyer flask, and Durham tubes.
• 🔥 Sterilization is a key step using an autoclave at 121°C for 45 minutes to sterilize the equipment.
• 🔬 Test samples are prepared by diluting at ratios of 1:91 for the test and dissolving lactose broth in distilled water.
• 🧫 The experiment uses 12 test tubes divided into two groups: one for sample dilution and the other for inoculation.
• 🧮 Serial dilutions of the sample are prepared at 10^-1, 10^-2, and 10^-3 concentrations.
• 💧 Inoculation is done by introducing diluted samples into the test tubes in groups A, B, and C.
• 🌡️ After inoculation, 9 mL of lactose broth is added to each test tube in groups A and B.
• 🔄 Durham tubes are inserted into each test tube to detect gas production, ensuring no air is trapped.
• ⏳ The final step involves incubating the samples for 24 hours at 37°C to observe results.

Q & A

What is the purpose of this experiment?

The purpose of the experiment is to test for coliform bacteria and E. coli using the MPN (Most Probable Number) method.

What materials are needed for the experiment?

Materials include lactose broth medium, distilled water (aquades), 12 test tubes, spirit burner for sterilization, Erlenmeyer flask, beaker glass, spatula, watch glass, pipettes, Durham tubes, and alcohol for aseptic work.

What is the first step in the procedure?

The first step is to prepare the sample by weighing it and dissolving it in a 1:91 ratio with the solvent (aquades).

How is the lactose broth medium prepared?

To prepare the lactose broth, 3 grams of lactose broth is weighed and dissolved in 50 mL of aquades in an Erlenmeyer flask, then stirred until homogeneous.

What is the sterilization process for the materials?

Sterilization is done using an autoclave for 45 minutes (30 minutes heating and 15 minutes sterilization) at 121°C. Items like the lactose broth, test tubes, Durham tubes, and stirrers are sterilized.

How are the test tubes divided for the inoculation process?

The 12 test tubes are divided into two parts: 3 test tubes for sample dilution (10^-1, 10^-2, and 10^-3) and 9 test tubes for sample inoculation, which are further divided into 3 groups (A, B, and C) with 3 tubes in each group.

What is the purpose of the serial dilution?

The purpose of serial dilution is to reduce the concentration of the sample, preparing it for inoculation into the lactose broth medium. Dilutions include 10^-1, 10^-2, and 10^-3.

How is the inoculation performed?

Inoculation is performed by adding 1 mL of the diluted sample from each concentration (10^-1, 10^-2, and 10^-3) to three respective test tubes in groups A, B, and C, followed by adding 9 mL of lactose broth to each tube.

What is the role of the Durham tubes in this experiment?

Durham tubes are placed inside the test tubes, inverted, to capture any gas produced by coliform bacteria, indicating fermentation.

What is the final step of the procedure?

The final step is to incubate the test tubes containing the samples and lactose broth at 37°C for 24 hours, allowing for bacterial growth and gas production.